Poly(ethylene oxide)-assisted energy funneling for efficient perovskite light emission. Issue 27 (19th June 2019)

• Record Type: Journal Article
• Authors: Xu, Tianfei; Meng, Yan; Wang, Miaosheng; Li, Mingxing; Ahmadi, Mahshid; Xiong, Zuhong; Yan, Shubin; Chen, Ping; Hu, Bin
• Is Part Of: Journal of materials chemistry. Volume 7:Issue 27(2019)
• Page Start: 8287
• Page End: 8293
• Publication Date: 2019-06-19
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c9tc01906e
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Poly(ethylene oxide)-assisted energy funneling was explored in perovskite polycrystals, achieving a very high PLQY of 62.1% in the poly(ethylene oxide):FAPbBr3 film. Abstract : Poly(ethylene oxide) (PEO) has been demonstrated as an effective polymer additive for fabrication of organic–inorganic hybrid perovskite light emitting devices due to its properties enabling pinhole-free film morphology, improved charge injection, and defect passivation. In this paper, we report a new aspect of PEO in assisting the energy funneling in formamidinium lead bromide (FAPbBr3 ) thin films, leading to a very high photoluminescence quantum yield of ∼62.1%. By mixing PEO with FAPbBr3 at a desired ratio, self-assembled 3D polycrystals with sizes from ∼20 to ∼1500 nm were formed. The polycrystals contain inhomogeneous domains with a range of energetic excited states. Through fluorescence lifetime image microscopy, the in situ fluorescence emissions and the lifetimes of the domains were measured simultaneously, indicating energy funneling from the wide-bandgap domains (with small-size grains) into the narrow-bandgap domains (with large-size grains). PL spectroscopy on the nano-second scale was used to study the dynamics of charge transfer, which shows a reduced short-wavelength emission and narrowed full width at half maximum with increasing time. Our results also indicate that the optimal PEO doping ratio of 0.35 : 1 can facilitate the most efficient charge carrier cascade for energy funneling. This study establishes the role of PEO-assisted energy funneling avoiding the defect-quenching effect in perovskites, for potential applications in perovskite LEDs and lasers.